The objective is to provide students, educators and researchers accurate, inexpensive, and accessible visual information on human embryonic development. Aligned digital images of the serial sections of the best, normal human embryos in the Carnegie collection will be made available on computer disks (DVDs). The serial sections of one specimen from each of the 23 stages present in the collection will be digitally duplicated. Two stages will include also the sections of a second specimen to demonstrate variations giving a total of 25 specimens. The stages cover the most critical time of prenatal development when all of the body systems are laid down and most serious malformations begin. The sections will be captured digitally at the site of the collection. The data will be stored temporarily on disks and sent to the PI's lab where the section images will be aligned, digitally enhanced, contoured, labeled and the specimen's external surface 3D reconstructed. A page will be constructed for each section image totaling approximately 8,000. To facilitate orientation each page will be accompanied by a small 3D reconstruction of the specimen's external surface showing the level and plane of the section. It will contain also a measuring bar showing the magnification and the specimen, section and section location numbers. The sections on each specimen will be captured at 20x magnification and 2K x 3K resolution using an automated capture method. They will be displayed in alignment and in sequence from top to bottom. Unique as well as representative structures will be labeled with leader lines. Technical information on each specimen will be included in an Introduction. The user will be able to select for viewing particular groups of sections (e.g., brain), labeled sections and varying resolutions. The DVDs will be replicated commercially and made available at a nonprofit fee of approximately 20 dollars each (includes handling, shipping and replacement). Users will be able to visualize the section images on stations currently available in many instances at their own institutions. An investment of 1200 dollars for an imaging station will permit any user to visualize for the first time in their own facility the microscopic sectional morphology of human embryos at each stage, in color and at high resolution and scroll easily through the aligned serial sections, one after another. A total of approximately six DVDs will hold all of the compressed sectional data on all of the specimens and will be available for purchase by mail. The DVDs will enable students to learn human embryology from actual embryos; enable educators to produce many varied instructional media on human embryonic development; and provide a valuable reference for developmental biologists.